TCP SYN (p0f)

4:52+12:0:1380:65535,13:mss,sok,ts,nop,ws:df,id+:0

first seen 2026-07-01 16:15 · last seen 2026-10-23 22:46 · JSON

Inconsistencies

User-Agents observed with this fingerprint that contradict what it proves at the wire. all inconsistencies →

fingerprint User-Agent claims wire shows confidence seen first seen last seen

4:52+12:0:1380:65535,13:mss,sok,ts,nop,ws:df,id+:0

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleW…

User-Agent claims Windows

TCP SYN initial TTL 52+12 indicates Unix-like

The initial TTL is set by the sending kernel (64 on Unix-like systems, 128 on Windows) and survives NAT. But VPNs, proxies and tunnels legitimately replace the sending stack, so this check never exceeds medium confidence.

Full User-Agent	Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36
Observed TTL	52+12 (observed + path distance → initial)
Claimed OS	Windows
Confidence	low — single sighting of an environmental signal

low

2026-07-01

Distinct clients per day (last 30 days, peak 28/day)

Distinct clients are counted by IP-hash per complete UTC day — unlike observation counts this is insensitive to one chatty client, but NAT merges clients and address rotation splits them.

Decomposed attributes

IP version	`4`
Initial TTL	`52+12`
Options length	`0`
MSS	`1380`
Window size	`65535`
Window scale	`13`
Options layout	`mss,sok,ts,nop,ws`
Quirks	`df,id+`
Payload class	`0`

Co-observed signals

Signals from other families seen in the same observation. A fingerprint spread thinly across many lower-layer signatures is a classic inconsistency signal.

TLS ClientHello (JA4)

fingerprint	co-occurrences
`t13d3013h2_1d37bd780c83_8537cf56674e` Match?Exact match in Thumbprint's published controlled catalog captures: curl 8.18.0.The fingerprint page shows the full measured match list. More on the catalog.	29
`t13d1511h2_8daaf6152771_78e6aca7449b`	3
`t13d180900_796efca44d18_1497af28dee9`	2

HTTP request (JA4H)

fingerprint	co-occurrences
`ge20nn030000_bf75ddd0bb29_000000000000_000000000000`	29
`ge11nn16enus_0d6ca22ab264_000000000000_000000000000`	2
`ge20nr09enus_5ad46a65401a_000000000000_000000000000` Match?Exact match in Thumbprint's published controlled catalog captures: safari 26.5.2, safari 26.6.2, safari 26.6.1, +3 more.The fingerprint page shows the full measured match list. More on the catalog.	1
`ge20nr08enus_1945e0741196_000000000000_000000000000`	1
`ge20nr09enus_8612527b17b8_000000000000_000000000000`	1

HTTP/2 frames (Akamai)

fingerprint	co-occurrences
`3:100;4:65536;2:0\|1048510465\|0\|m,s,a,p` Match?Exact match in Thumbprint's published controlled catalog captures: curl 8.13.0, curl 8.18.0, curl 8.21.0, +8 more.The fingerprint page shows the full measured match list. More on the catalog.	29
`2:0;4:2097152;5:16384;6:16777216\|5177345\|0\|m,s,a,p`	3

TCP SYN (JA4T)

fingerprint	co-occurrences
`65535_2-4-8-1-3_1380_13`	34

User-Agent

fingerprint	co-occurrences
`curl/8.14.1`	29
`Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/27.0 Safari/605.1.15`	3
`Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36`	2

Country

fingerprint	co-occurrences
`US` · United States	11
`CH` · Switzerland	3
`PL` · Poland	3
`AU` · Australia	2
`NO` · Norway	2
`BE` · Belgium	2
`NZ` · New Zealand	2
`FI` · Finland	2
`DE` · Germany	1
`SE` · Sweden	1

Network (ASN)

fingerprint	co-occurrences
`AS13335` · Cloudflare, Inc.	34

TLS supported groups

fingerprint	co-occurrences
`11ec,001d,0017,001e,0018,0019,0100,0101` Match?Exact match in Thumbprint's published controlled catalog captures: python-httpx 0.28.1, python-requests 2.34.2, curl 8.23.0, +4 more.The fingerprint page shows the full measured match list. More on the catalog.	29